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CORRECTING  FOR  SLOPE
RECORDING   NOTES   FOR   SLOPE Chaining

Engineering Aid 3 - Beginning Structural engineering guide book
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Preparing Chaining Notes Before   discussing   the   subject   of   chaining notes,  we  will  mention  a  few  general  principles applicable  to  all  types  of  field  notes.  It  goes without saying that it is essential that measure- ments and other data be accurately recorded and that  any  additional  information  required  to identify  and  clarify  the  data  be  included. Field notes are required to be legible as well as  accurate.  If  you  don’t  write  or  print  legibly, you  will  have  to  improve  your  script.  All  notes should be recorded in pencil; a 3H or 4H pencil is best for the job. A pencil that is too soft blunts too  quickly;  one  that  is  too  hard  makes  a  faint mark and scores the paper. In the field, you need to carry a pocketknife or pocket pencil sharpener to  keep  your  pencil  sharpened  or  pointed. There  is  a  general  rule  to  the  effect  that erasures  are  not  permitted  in  field  notes.  Suppose that in the course of chaining several intervals you make  a  10-ft  “bust”  in  one  of  the  intervals  by misreading 10 ft as 20 ft. After you total up the distance, some circumstance leads you to suspect that  the  total  is  off.  You  recheck  the  work  and discover where you made the bust. The notebook record  for  that  interval  must  be  changed.  You make the change by crossing out the wrong entries and  entering  the  correct  ones  above  them—not by  erasing  the  wrong  entries. RECORDING  NOTES  FOR  HORIZONTAL CHAINING.— A typical example of a horizontal chaining conducted for a closed traverse is shown in  figure  12-16.  The  chaining  party  started  at station  A  and  chained  around  by  way  of  B,  C, and so on. Arriving back at A, the party reversed its direction and chained back around by way of E,  D,  C,  and  so  on,  as  a  check.  The  distance finally  recorded  for  each  traverse  line  was  the mean  (average)  between  the  forward  measurement and  the  backward  measurement. Note on the bottom left-hand side the fact that the tape had a standard error of 0.013 ft per 100 ft  of  tape.  The  error  is  marked  “  +  ,”  meaning that the amount of error should be added to the measurement  as  indicated  by  the  tape.  Obviously, the tape was reading short. The  corrections  in  the  “Correction”  column indicate  that  only  correction  for  standard  error Figure 12-16.-Notes for horizontal chaining. 12-19







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